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Bats avoid radar installations: could electromagnetic fields deter bats from colliding with wind turbines?

Nicholls B, Racey PA - PLoS ONE (2007)

Bottom Line: At each radar station bat activity was recorded three times with three independent sampling points monitored on each occasion, resulting in a total of 90 samples, 30 of which were obtained within each field strength category.Bat activity was significantly reduced in habitats exposed to an EMF strength of greater than 2 v/m when compared to matched sites registering EMF levels of zero.The reduction in bat activity was not significantly different at lower levels of EMF strength within 400 m of the radar.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Aberdeen, Aberdeen, United Kingdom. b.nicholls@abdn.ac.uk

ABSTRACT
Large numbers of bats are killed by collisions with wind turbines, and there is at present no direct method of reducing or preventing this mortality. We therefore determine whether the electromagnetic radiation associated with radar installations can elicit an aversive behavioural response in foraging bats. Four civil air traffic control (ATC) radar stations, three military ATC radars and three weather radars were selected, each surrounded by heterogeneous habitat. Three sampling points matched for habitat type and structure, dominant vegetation species, altitude and surrounding land class were located at increasing distances from each station. A portable electromagnetic field meter measured the field strength of the radar at three distances from the source: in close proximity (<200 m) with a high electromagnetic field (EMF) strength >2 volts/metre, an intermediate point within line of sight of the radar (200-400 m) and with an EMF strength <2 v/m, and a control site out of sight of the radar (>400 m) and registering an EMF of zero v/m. At each radar station bat activity was recorded three times with three independent sampling points monitored on each occasion, resulting in a total of 90 samples, 30 of which were obtained within each field strength category. At these sampling points, bat activity was recorded using an automatic bat recording station, operated from sunset to sunrise. Bat activity was significantly reduced in habitats exposed to an EMF strength of greater than 2 v/m when compared to matched sites registering EMF levels of zero. The reduction in bat activity was not significantly different at lower levels of EMF strength within 400 m of the radar. We predict that the reduction in bat activity within habitats exposed to electromagnetic radiation may be a result of thermal induction and an increased risk of hyperthermia.

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Related in: MedlinePlus

The differences in: (a) log bat active minutes (high EMF minus control).A negative value indicates that bat activity was higher at the control site than at the site subject to a high electromagnetic field strength (>2 v/m). (b) log total number of bat passes (high EMF minus control). Each triad of differences represent a single radar site (n = 10).
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pone-0000297-g002: The differences in: (a) log bat active minutes (high EMF minus control).A negative value indicates that bat activity was higher at the control site than at the site subject to a high electromagnetic field strength (>2 v/m). (b) log total number of bat passes (high EMF minus control). Each triad of differences represent a single radar site (n = 10).

Mentions: Total bat activity (bat active minutes) was higher in the control sites (0 v/m) when compared to sites exposed to a high level (>2 v/m) of electromagnetic radiation. Paired t tests carried out on the log-transformed bat active minutes, recorded by the automatic bat recording stations, showed that bats were significantly more active in control sites when compared to high EMF sites (t = 4.41; n = 10; p = 0.003; Fig. 2a). The number of bat passes (all species) recorded during transects with the frequency division detector was also higher in the control sites when compared to sites exposed to a high level of electromagnetic radiation. Paired t tests carried out on the log transformed number of bat passes, showed that bats were significantly more active in control sites when compared to high EMF sites (t = 4.86; n = 10; p = 0.001; Fig. 2b).


Bats avoid radar installations: could electromagnetic fields deter bats from colliding with wind turbines?

Nicholls B, Racey PA - PLoS ONE (2007)

The differences in: (a) log bat active minutes (high EMF minus control).A negative value indicates that bat activity was higher at the control site than at the site subject to a high electromagnetic field strength (>2 v/m). (b) log total number of bat passes (high EMF minus control). Each triad of differences represent a single radar site (n = 10).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC1808427&req=5

pone-0000297-g002: The differences in: (a) log bat active minutes (high EMF minus control).A negative value indicates that bat activity was higher at the control site than at the site subject to a high electromagnetic field strength (>2 v/m). (b) log total number of bat passes (high EMF minus control). Each triad of differences represent a single radar site (n = 10).
Mentions: Total bat activity (bat active minutes) was higher in the control sites (0 v/m) when compared to sites exposed to a high level (>2 v/m) of electromagnetic radiation. Paired t tests carried out on the log-transformed bat active minutes, recorded by the automatic bat recording stations, showed that bats were significantly more active in control sites when compared to high EMF sites (t = 4.41; n = 10; p = 0.003; Fig. 2a). The number of bat passes (all species) recorded during transects with the frequency division detector was also higher in the control sites when compared to sites exposed to a high level of electromagnetic radiation. Paired t tests carried out on the log transformed number of bat passes, showed that bats were significantly more active in control sites when compared to high EMF sites (t = 4.86; n = 10; p = 0.001; Fig. 2b).

Bottom Line: At each radar station bat activity was recorded three times with three independent sampling points monitored on each occasion, resulting in a total of 90 samples, 30 of which were obtained within each field strength category.Bat activity was significantly reduced in habitats exposed to an EMF strength of greater than 2 v/m when compared to matched sites registering EMF levels of zero.The reduction in bat activity was not significantly different at lower levels of EMF strength within 400 m of the radar.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Aberdeen, Aberdeen, United Kingdom. b.nicholls@abdn.ac.uk

ABSTRACT
Large numbers of bats are killed by collisions with wind turbines, and there is at present no direct method of reducing or preventing this mortality. We therefore determine whether the electromagnetic radiation associated with radar installations can elicit an aversive behavioural response in foraging bats. Four civil air traffic control (ATC) radar stations, three military ATC radars and three weather radars were selected, each surrounded by heterogeneous habitat. Three sampling points matched for habitat type and structure, dominant vegetation species, altitude and surrounding land class were located at increasing distances from each station. A portable electromagnetic field meter measured the field strength of the radar at three distances from the source: in close proximity (<200 m) with a high electromagnetic field (EMF) strength >2 volts/metre, an intermediate point within line of sight of the radar (200-400 m) and with an EMF strength <2 v/m, and a control site out of sight of the radar (>400 m) and registering an EMF of zero v/m. At each radar station bat activity was recorded three times with three independent sampling points monitored on each occasion, resulting in a total of 90 samples, 30 of which were obtained within each field strength category. At these sampling points, bat activity was recorded using an automatic bat recording station, operated from sunset to sunrise. Bat activity was significantly reduced in habitats exposed to an EMF strength of greater than 2 v/m when compared to matched sites registering EMF levels of zero. The reduction in bat activity was not significantly different at lower levels of EMF strength within 400 m of the radar. We predict that the reduction in bat activity within habitats exposed to electromagnetic radiation may be a result of thermal induction and an increased risk of hyperthermia.

Show MeSH
Related in: MedlinePlus